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Dairy cattle powerpoint

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Dairy cattle powerpoint

  1. 1. Dairy Cattle Heat Stress
  2. 2. • A magnitude of forces external to the body which tend to displace its system from resting or ground state. (Youself, 1985) • Heat stress happens in animals when there is problem in thermoregulation. When there is an imbalance between heat production (gain) within the body and its dissipation (loss) from the body. What is STRESShttp://en.engormix.com/MA-dairy-cattle/articles/heat-stress-dairy-animals-t1019/p0.htm
  3. 3. Factors that determine the level of environmental heat loss or gain: •Air temperature and relative humidity •Amount of solar radiation •Degree of night cooling •Ventilation and air flow •Length of the hot conditions * Domestic livestock have evolved a range of physiological strategies to off-load heat to cope in hot environmental conditions. Problems may occur if temperatures and humidity remain high and cows do not have opportunities to get rid of excess heat.http://en.engormix.com/MA-dairy-cattle/management/articles/heat-stress-in-dairy-t2165/124-p0.htm
  4. 4. Environmental Stress Physiological Nutritional ManagementToxic metal pollutants Heat Stress Acidosis HandlingChemical Fertilizers Advance pregnancy Bloat TransportationPesticide Dehydration Hypocalcaemia Seasonal changecontamination Cold stress Ketosis Hypomagnesaemia Mycotoxin/Plant- toxins • Heat stress accounts for a large portion of dairy cattle culled. The four types of stresshttp://en.engormix.com/MA-dairy-cattle/articles/heat-stress-dairy-animals-t1019/p0.htm
  5. 5. • Based on maximizing available routes of heat exchange with • Convection • Conduction • Radiation • Evaporation.• When ambient temperature conditions approach body temperature, the only viable route of heat loss is evaporation; if ambient conditions exceed body temperature, heat flow will reverse and the animal becomes a heat sink.• THI allows us to estimating the thermal environment around animals. This index takes into account ambient air temperature and humidity. Successful cooling strategies for lactating dairy cows
  6. 6. The Stress levels and THI numberhttp://en.engormix.com/MA-dairy-cattle/management/articles/heat-stress-in-dairy-t2165/124-p0.htm
  7. 7. Lactating cows prefer an ambient temperature between 5 and 25º C, thethermo-neutral zone (TNZ). Heat stress is caused by both temperature aswell as humidityhttp://en.engormix.com/MA-dairy-cattle/management/articles/heat-stress-in-dairy-t2165/124-p0.htm
  8. 8. The two main strategies to improve heat stress during summer months in animals 1. Management Approach • Shades : It is the cheapest way to avoid heat stress in cattle. • Milking times: On hot days we must milk and feed animals before 8 am in the morning. • In hot summer months sprinkling of dairy animals before morning and evening milking period. • Drinking water 2. Nutritional Approach • During summer period, it is recommended that 75 % of green fodder feeding. • Feeding of total mixed rations I • Increase the energy density of diet. • Increase the feeding frequency during cooler period of the day • Feeding of by-pass nutrients helps to improve nutrient density and availability for better milk production • Further, supplementation of nutrients which play role as antioxidantshttp://en.engormix.com/MA-dairy-cattle/articles/tips-keeping-dairy-cows-t989/p0.htm
  9. 9. Heat stress, with its physiological and behavioral consequences, increases the risks of rumen acidosis.http://www.thecattlesite.com/articles/1053/heat-stress-in-dairy-cows-implications-and-nutritional-management
  10. 10. Non-visual heat stress• Sub-clinical rumen acidosis increases• Blood flow to internal organs decreases• Reproduction performance decreases• Decreased levels of blood bicarbonate• Significant drop in pregnancy rate• Death loss increases• Blood flow to skin increasesVisual heat stress• Daily feed intake decreases• Water intake increases• Respiration rates increase• Acute health problems• Milk production decreases• High incidence of abortions• Decreased saliva production• Increased droolinghttp://www.formafeed.com/products/products_dairy_hydrolac.htm
  11. 11. • Ideal ambient temperature for dairy cattle is between 41° and 77°F.• Cows are stressed when their respiration rate rises above 75-80 breaths per minute.• Contribute to heat stress • High humidity levels • low air velocities • solar radiationhttp://en.engormix.com/MA-dairy-cattle/articles/tips-keeping-dairy-cows-t989/p0.htm http://www.formafeed.com/products/products_dairy_hydrol ac.htm
  12. 12. • Lactating dairy cows feel heat stress when the rectal temperature is higher than 39.4C• THI = 0.72 (W+D) +40.6,Where W = Wet bulb temperature oC and D=Dry bulb temperature oC• THI values: • 70F or less are considered comfortable • 75-78F stressful • >78F causes extreme distress with lactating cows being unable to maintain thermo regulatory mechanisms
  13. 13. • Heat stressed cows generally exhibit altered blood acid-base chemistry as a result of the shift in cooling from conductive, convective, and radiation to evaporative cooling (Kibler and Brody, 1950).• Panting and sweating increase as the reliance on evaporative cooling increases. • Panting sharply increases the loss of CO2 via pulmonary ventilation, reducing the blood concentration of carbonic acid.• For lactating dairy cows the ambient temperatures above 25C are associated with lower feed intake, drops in milk production and reduced metabolic rate (Berman, 1968).• Clean drinking water is arguably the most important nutrient for the dairy cow• *Texas research work demonstrated that offering chilled drinking water enhanced milk yield for lactating cows (Milam et al., 1986) by reducing body temperature through absorbed heat energy. Effects of Heat Stress on Physiology
  14. 14. Temperature Humidity Index for Dairy Cows, if the temperature is 95°F and the humidity is 75%humidity the cow is under “severe” stress.http://en.engormix.com/MA-dairy-cattle/articles/tips-keeping-dairy-cows-t989/p0.htm
  15. 15. Temp - - - - - - - - Relative Humidity, % - - - - - - - - (F) 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 - - - - - - - - - - - - - - - - - - - - - THI - - - - - - - - - - - - - - - - - - 70 64 64 64 65 65 65 66 66 66 67 67 67 68 68 68 69 69 69 70 70 71 64 65 65 65 66 66 66 67 67 67 68 68 68 69 69 70 70 70 71 71 Heat Stress 72 65 65 65 66 66 67 67 67 68 68 69 69 69 70 70 70 71 71 72 72 Begins 73 65 66 66 66 67 67 68 68 68 69 69 70 70 71 71 71 72 72 73 73 74 66 66 67 67 67 68 68 69 69 70 70 70 71 71 72 72 73 73 74 74 75 67 67 67 68 68 68 69 69 70 70 71 71 72 72 73 73 74 74 75 75 76 67 67 68 68 69 69 70 70 71 71 72 72 73 73 74 74 75 75 76 76 Sharp drops in 77 67 68 68 69 69 70 70 71 71 72 72 73 73 74 74 75 75 76 76 77 productio n occur 78 68 68 69 69 70 70 71 71 72 73 73 74 74 75 75 76 76 77 77 78 79 68 69 69 70 70 71 71 72 73 73 74 74 75 76 76 77 77 78 78 79 80 69 69 70 70 71 72 72 73 73 74 75 75 76 76 77 78 78 79 79 80 81 69 70 70 71 72 72 73 73 74 75 75 76 77 77 78 78 79 80 80 81 82 69 70 71 71 72 73 73 74 75 75 76 77 77 78 79 79 80 81 81 82 Danger Zone 83 70 71 71 72 73 73 74 75 75 76 77 78 78 79 80 80 81 82 82 83http://en.engormix.com/MA-dairy-cattle/management/articles/heat-stress-in-dairy-t2165/124-p0.htm THI chart
  16. 16. • When THI values are between 72 and 86, physical signs of heat stress with cattle are visible. When the THI is greater than 86, severe heat stress can be exhibited.http://www.formafeed.com/reference%20pages/hydrolac_heat_index_chart.htm
  17. 17. How to evaluate heat stress?Body temperature (rectal) >39.4ºCRespiratory frequency >100/mnDM intake decreases: -10% = high stress - 25% = severe stress• The dairy cattle thermal comfort zone is -13ºC - +25ºC.• A normal body temperature is between 38.4ºC and 39.1ºC (Lefebvre and Plamondon, 2003)http://www.thecattlesite.com/articles/1053/heat-stress-in-dairy-cows-implications-and-nutritional-management
  18. 18. Until recently, a 72 THI was considered the point when heat and humidity began to stress dairycows. University of Arizona researchers have found a 68 THI is a better indicator. Ontario, 2011
  19. 19. Calves the optimal thermal environment is between 55 to 78°F in still air. 78°F andabove, they must burn more energy to drive off heat from the body by sweating andincreasing respiratory rate. Broadwater, 2010
  20. 20. • Signs of heat stress become evident in dairy cows when the THI exceeds 72.http://www.milkproduction.com/Library/Scientific-articles/Housing/Coping-with-summer-weather/
  21. 21. • Temperature and humidity index do not include • air velocity • radiant heat • metabolic heat production • hair coat • skin water loss • posture effects Replacing a heat stress index based on air temperature and humidity by one based on equations including animal and environmental variables will help to determine the magnitude of the stress. The Problem with THI
  22. 22. Wet- and Dry- Bulb Temp• Wet-bulb dry temperature (WBDT)79) 0.4Tw+0.6Tahttp://www.jniosh.go.jp/en/indu_hel/pdf/indhealth_44_3_388.pdf
  23. 23. • Acclimation involves changes in hormonal signals as well as alteration in target tissue responsiveness to hormonal stimuli. • Determination that adaptation of animals to thermal stress is a homeorhetic process • endocrine control is an innovative way to use of endocrine regulation as means of improving thermal tolerance. Acclimation/Conditioninghttp://www.ncbi.nlm.nih.gov/pubmed/16537957
  24. 24. • Cows increase respiration rate in order to promote heat loss via evaporation. Respiration rate can be the most practical way to identify heat stress, as flank movements are easy to count.• Respiration rate increase in response to heat load with little or no lag in time (Brown-Brandl et al., 2005). • feedlot cattle, respiration rate increased from approximately 65 breaths/min when THI < 76 to 93 breaths/min when THI ≥ 84.• Cows are stressed when their respiration rate rises above 75-80 breaths per minute. Respiration Rate (RR) http://jas.fass.org/content/83/6/1377.full#ref-29
  25. 25. Innovative Technology • Intravaginal probes to track core body temperature (CBT) continuous by attaching to the intravaginal drug release (CIDR) device • measures core body temperature (CBT) every 60 seconds for up to 6 days. • This technology allows cows’ CBT to be monitored and recorded 24h/d as they move throughout all areas of a dairy facility.
  26. 26. • Infrared thermography guns has been shown to be a cheap and effective way to figure the actual skin surface temperature of an animal.• If the skin surface temperature is below 35°C, the temperature gradient between the core and skin is large enough for the animals to effectively use all 4 routes of heat exchange.• Infrared skin temperature is highly correlated with respiration rates and is a good measure of the microenvironment around the animal.http://www.ncbi.nlm.nih.gov/pubmed/16537957
  27. 27. Infrared image of a dairy cow lying down at night. The temperature scale is in Fahrenheit.• Standing has been shown to increase heat loss by increasing the amount of skin exposed to air flow or wind.• Recumbent animals may develop heat stress at lower ambient temperatures than standing animals.http://www.thedairysite.com/articles/2404/behavioural-responses-to-heat-stress
  28. 28. Cooling Ponds • Cooling ponds did have a lower percentage of successful breedings • Fewer days dry • A higher percentage of cows in milk compared with dairy herds that used other forms of cooling. “cooling ponds may provide relief from heat stress without adversely affecting most important measures of herd performance.” http://www.ncbi.nlm.nih.gov/pubmed/15905458
  29. 29. • Cortisol level will be 10 times higher than normal during periods of elevated environmental temperature and humidity. Heat stress takes heavy toll to dairy performance by way of making changes in feed intake, immunity and milk production.• The increase in body temperature affects the reproductive tract and the early embryo. These changes in the reproductive tract influence the ability of a cow to become pregnant during heat stress.http://en.engormix.com/MA-dairy-cattle/management/articles/heat-stress-in-dairy-t2165/124-p0.htm• “Higher producing cows exhibit humidity ranging more signs of heat stress than lower producing cows because higher pro-rapid shallow breathing, producing cows generate more heat as they eat more feed for higher production.” (Pennington)http://www.uaex.edu/other_areas/publications/pdf/fsa-3040.pdf• *Texas research work demonstrated that offering chilled drinking water enhanced milk yield for lactating cows by reducing body temperature through absorbed heat energy (Milam et al., 1986) .http://en.engormix.com/MA-dairy-cattle/articles/heat-stress-dairy-animals-t1019/p0.htm Extras
  30. 30. In order to maintain milk production, stress minimization was required for an unusually long period of time.Australian Government: Bureau of Meteorology
  31. 31. http://www.milkproduction.com/Library/Scientific-articles/Housing/Coping-with-summer-weather/
  32. 32. • Tunnel Ventilation • These systems have large exhaust fans located at one end of the barn, drawing the air into the building on the opposite end. • It provides both air exchange and airflow past the animals at higher air velocities in the barn during the summer’s hottest days. Although an excellent system, the electrical costs to run the fans can be high. • The inlet needs to be sized adequately to handle the airflow. Tunnel ventilation is not used in cold weather so tie-stall barns need a well-designed cold weather ventilation system.• Shade • A portable or temporary shade can reduce the amount of solar radiation that reaches cows on hot sunny days. Shade height should be 14ft or higher for maximum effectiveness to allow for good airflow under them. • Shade cloth is less expensive than solid roofing material but does not provide as much protection from solar radiation. If using a shade structure, feed and water must be available under the shade and a manure management system must be planned. • Cows will often lie down in the shade so some of the shaded area should be maintained for good cow comfort
  33. 33. http://www.wxforecastnow.com/wxbase/index.phpoption=com_content&view=article&id=12&Itemid=18
  34. 34. Proposed systems for rating heat stress and strain (heat stress indices) Year Index Author(s)1905 Wet-bulb temperature (Tw) Haldane19)1916 Katathermometer Hill et al.47)1923 Effective temperature (ET) Houghton & Yaglou23)1929 Equivalent temperature (Teq) Dufton48)1932 Corrected effective temperature (CET) Vernon & Warner24)1937 Operative temperature (OpT) Winslow et al.49)1945 Thermal acceptance ratio (TAR) Ionides et al.50)1945 Index of physiological effect (Ep) Robinson et al.51)1946 Corrected effective temperature (CET) Bedford52)1947 Predicted 4-h sweat rate (P4SR) McArdel et al.53)1948 Resultant temperature (RT) Missenard et al.54)1950 Craig index (I) Craig55)1955 Heat stress index (HIS) Belding & Hatch7)1957 Wet-bulb globe temperature (WBGT) Yaglou & Minard25)1957 Oxford index (WD) Lind & Hellon34)1957 Discomfort index (DI) Thom36)1958 Thermal strain index (TSI) Lee & Henschel56)1959 Discomfort index (DI) Tennenbaum et al.39)1960 Cumulative discomfort index (CumDI) Tennenbaum et al.39)1960 Index of physiological strain (Is) Hall & Polte57)1962 Index of thermal stress (ITS) Givoni58)1966 Heat strain index (corrected) (HSI) McKarns & Brief59)1966 Prediction of heart rate (HR) Fuller & Brouha60)
  35. 35. 1967 Effective radiant field (ERF) Gagge et al.61)1970 Predicted mean vote (PMV) Fanger9)Threshold limit value (TLV)1970 Prescriptive zone Lind62)1971 New effective temperature (ET*) Gagge et al.63)1971 Wet globe temperature (WGT) Botsford64)1971 Humid operative temperature Nishi & Gagge65)1972 Predicted body core temperature Givoni & Goldman66)1972 Skin wettedness Kerslake67)1973 Standard effective temperature (SET) Gagge et al.68)1973 Predicted heart rate Givoni & Goldman69)1978 Skin wettedness Gonzales et al.70)1979 Fighter index of thermal stress (FITS) Nunneley & Stribley71)1981 Effective heat strain index (EHSI) Kamon & Ryan72)1982 Predicted sweat loss (msw) Shapiro et al.73)1985 Required sweating (SWreq) ISO 793374)1986 Predicted mean vote (modified) (PMV*) Gagge et al.75)1996 Cumulative heat strain index (CHSI) Frank et al.76)1998 Physiological strain index (PSI) Moran et al.77)1999 Modified discomfort index (MDI) Moran et al.78)2001 Environmental stress index (ESI) Moran et al.79)2005 Wet-bulb dry temperature (WBDT) Wallace et al.80)2005 Relative humidity dry temperature (RHDT) Wallace et al.80)
  36. 36. • http://en.engormix.com/MA-dairy-cattle/articles/heat-stress-dairy-animals-t1019/p0.htm• •http://en.engormix.com/MA-dairy-cattle/management/articles/heat-stress-in-dairy-t2165/124- p0.htm• •http://en.engormix.com/MA-dairy-cattle/articles/heat-stress-dairy-animals-t1019/p0.htm• •http://en.engormix.com/MA-dairy-cattle/management/articles/heat-stress-in-dairy-t2165/124- p0.htm• •http://en.engormix.com/MA-dairy-cattle/management/articles/heat-stress-in-dairy-t2165/124- p0.htm• •http://en.engormix.com/MA-dairy-cattle/articles/tips-keeping-dairy-cows-t989/p0.htm •http://www.thecattlesite.com/articles/1053/heat-stress-in-dairy-cows-implications-and-nutritional- management• •http://www.formafeed.com/products/products_dairy_hydrolac.htm• •http://en.engormix.com/MA-dairy-cattle/articles/tips-keeping-dairy-cows-t989/p0.htm •http://www.formafeed.com/products/products_dairy_hydrolac.htm• •http://en.engormix.com/MA-dairy-cattle/articles/tips-keeping-dairy-cows-t989/p0.htm •http://en.engormix.com/MA-dairy-cattle/management/articles/heat-stress-in-dairy-t2165/124- p0.htm• •http://www.formafeed.com/reference pages/hydrolac_heat_index_chart.htm• •http://www.jniosh.go.jp/en/indu_hel/pdf/indhealth_44_3_388.pdf• •http://www.milkproduction.com/Library/Scientific-articles/Housing/Coping-with-summer-weather/ •http://www.ncbi.nlm.nih.gov/pubmed/16537957 •http://jas.fass.org/content/83/6/1377.full• •http://www.thecattlesite.com/articles/1053/heat-stress-in-dairy-cows-implications-and-nutritional- management

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